Don't cache the json data

calendar/redirect.php

@@ -1,4 +1,8 @@
 <?php
+header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
+header("Cache-Control: post-check=0, pre-check=0", false);
+header("Pragma: no-cache");
+
 /**
 This script redirects all calls to the real Web Service.
 This is required to allow AJAX calls as cross-domain requests are normally not allowed.